Extractive Pressure-swing Distillation Research Articles

Heat Pump-Assisted Extractive Pressure-Swing Distillation with Integrated Feed Preconcentration/Solvent Recovery for Isopropanol-Benzene-Water Separation

Recently, heat-integrated pressure-swing distillation (HIPSD) has been explored for recovering isopropanol and benzene from wastewater, but the process remains highly energy-intensive. Given the dilute nature of the feed, intensified extractive distillation with an integrated preconcentration column (IED) is more suitable. However, previous researches have often overlooked the critical role of pressure and lacked rigorous optimization of operating pressure in such systems. In this article, we developed novel extractive pressure-swing distillation with integrated feed preconcentration/solvent recovery column (IEPSD) by introducing a pressure-swing configuration and incorporate energy-saving technologies to achieve more sustainable and cost-effective separation processes. First, thermodynamic analysis is conducted to explore the effect of pressure on extractive pressure-swing distillation. Then, a parallel genetic algorithm is applied for rigorous optimization, followed by the application of heat integration and heat pump. The IEPSD is superior to IED in terms of total annual cost (TAC) and CO2 emission. With the inclusion of energy-saving technologies, IEDHI and IEPSDHI further reduced TAC by 5.29% and 7.40%, and cut CO2 emissions by 25.18% and 24.03%, respectively, compared to their base processes. The use of a heat pump is particularly advantageous for IEPSD due to its lower boiling temperatures under vacuum pressure, leading to the development of IEPSDHIHP, which offered an additional 22.36% CO2 reduction and marginally lower TAC than IEPSDHI. Ultimately, IEPSDHIHP proves to be the best option, offering a 51.15% TAC reduction and 68.42% CO2 emissions reduction compared to HIPSD. In summary, the developed IED and IEPSD processes, especially with heat integration and heat pump technologies, offer significant economic and environmental advantages over conventional HIPSD.

Mechanism Analysis and Multiobjective Optimization of Efficient and Energy-Saving Separation of Green Fuel Additives via Extractive Pressure Swing Distillation with an Ionic Liquid Mixed Entrainer

Mechanism Analysis and Multiobjective Optimization of Efficient and Energy-Saving Separation of Green Fuel Additives via Extractive Pressure Swing Distillation with an Ionic Liquid Mixed Entrainer

A novel sustainable separation process based on special azeotropic behavior of benzene/ethanol/butanone: Process design and multi-performance evaluation

Special azeotropic behaviors of complex mixtures can be used to develop distillation processes to realize energy-saving separation. Based on the residual curves of the system at different pressures and an examination of the impact of several extractants on the relative volatility, the pressure-swing distillation (PSD) process and the extractive distillation (ED) process were proposed to separate benzene/ethanol/butanone azeotrope. According to the characteristic of the azeotropic disappearance of ethanol/butanone with increasing pressure, two new extractive pressure-swing distillation (EPSD) processes were developed and compared with PSD as well as ED. To be able to determine the optimal operating parameters for various processes, the non-dominated sorting genetic algorithm II (NSGA-Ⅱ) was utilized. Heat integration was designed for the EPSD processes to reduce energy consumption. The above processes were evaluated in four aspects of the economy, energy, environment and exergy. The relationship between the four performances of different processes and the normal distance was discussed. The results indicate that the EPSD processes show better performance than the ED and PSD processes. Compared with the two EPSD processes, the total annual cost (TAC) of the heat integrated EPSD processes (HI-EPSD) was reduced by 13.2% and 14.4%, the total gas emissions of CO2, SO2 and NOX were also reduced by 23.6% and 27.2%, respectively. Hence, coupling the ED process with the PSD process and heat integration can both better improve the separation performance of distillation.

Process design and 4E analysis of different distillations of ethyl acetate/ethanol/cyclohexane separation based on extractive and pressure-swing properties

In this study, we proposed and compared extractive distillation, extractive pressure-swing distillation (EPSD), and pressure-swing distillation (PSD) techniques for the efficient separation of the ethyl acetate/ethanol/cyclohexane pressure-sensitive azeotropic mixture. Based on the influence of the extractant on the relative volatility and the analysis of the ternary phase diagram, dimethyl sulfoxide was selected as the extractant for extractive distillation. The pressure range for PSD was also determined. We employed the non-dominated sorting genetic algorithm II to optimize different processes, considering equipment and operation costs as the objective functions. After the multi-objective optimization, the decision solution was selected using the minimum distance method. A heat exchange network was also used to explore the energy-saving effects of different processes. The aforementioned processes were comprehensively evaluated based on economic, energy, environmental, and exergy analyses. The process results were correlated with the phase diagram based on the normal distance. The total annual cost, energy consumption, gas emissions, and energy loss of the improved processes decreased by more than 10%, 15%, 16%, and 3%, respectively, compared to those of the conventional process. Among the conventional and improved processes, EPSD and heat-integrated EPSD were identified as the best, respectively.

Economic, environmental, energy and exergy analysis and multi-objective optimization for efficient purification of a friendly gasoline additive by extractive distillation coupled with pervaporation

Ethyl tert-butyl ether, an environmentally friendly gasoline additive, has high industrial application value, which is very necessary to study the refined process. The development of an efficient ternary azeotropic separation and purification process promotes the establishment of an environment-friendly society. In this study, two common methods of extractive distillation and extractive pressure swing distillation and three enhanced methods of heat integration process and coupled pervaporation technology were used to efficiently separate ethyl tert-butyl ether/ethanol/water. The most effective and environmentally friendly extractants were screened by analyzing the effects of relative volatility, intermolecular interactions and biotoxicity. The multi-objective optimization method was adopted to optimize the process with the annual total cost and gas emissions as the goals and the optimal parameters and process plans for extractive distillation and extractive pressure swing distillation were obtained. Finally, five technological processes are analyzed from the aspects of economy, environment, energy and exergy. It was found that the use of pressure swing distillation would greatly increase the economic and energy loss. And compared with the conventional process, the total annual cost of the extractive distillation coupled pervaporation process was reduced by 15.12 % and the environment was reduced by 20.17%. The coupling process that is of great significance to the purification of ethyl tert-butyl ether, an environmentally friendly gasoline additive was superior to the single distillation process in terms of economy, environment and energy.